Spatial evolution of radial void and bubble size distributions in CO₂-water gas-liquid bubbly flows in a vertical pipe were measured using a conductivity probe and an image processing method. Numerical simulations were carried out using a three-dimensional one-way bubble tracking method with a mass transfer model, which takes into account the accumulation of surfactants on bubble surface and the absorption and desorption of gas components. As a result, the following conclusions were obtained: (1) the decreasing rate of the total gas volume decreases in the flow direction due to the desorption of N₂ and O₂, the accumulation of surfactants and the bubble volume expansion due to the decrease in static pressure, and (2) the bubble tracking method gave good predictions for the bubble dissolution process in CO₂-water bubbly pipe flows.